1. Field of the Invention
The present invention relates to a method used in a numerical control apparatus for displaying objects such as the shapes of materials and tools contained in machining programs for numerical control apparatuses, and more particularly to a method used in numerical control apparatuses for displaying objects which are moved together with the servo axis during a machining simulation.
2. Description of the Related Art
Some numerical control apparatuses to control machine tools display animation of a simulation of machining by machine tools on a CRT screen connected thereto, based on the shapes of the materials and tools contained in the machining programs. However, in conventional simulation, numerical control apparatuses can display only the movements of tools for machining materials on the display screen.
The following is a description of a conventional machining simulation, with reference to the drawings. FIGS. 4 and 5 illustrate display screens of a conventional numerical control apparatus. a tool shape 3. The material shape 2, one end of which is fixed by a chuck, rotates in the direction of the C-axis, and the tool shape 3 shifts together with the servo axis in the directions of the X-axis and the Z-axis. Therefore, the shift of the tool shape 3 in the directions of the X-axis and the Z-axis, and the machining thereby of the material shape 2 according to the machining program, is displayed on the display screen 1 as machining simulation. Namely, the tool shape 3 is shifted from the position shown in FIG. 4, in the directions of the X-axis and the Z-axis, to the position shown in FIG. 5. The display of the material shape 2, on the other hand, shows only the rotation thereof in the direction of the C-axis when cut by the tool shape 3 and, the relative positional relationship therebetween on display screen 1 is not changed.
In practice, however, with some actual machine tools such as a compound and a multi-system lathe, the tool and the material shift independently. For example, the tool is shifted in the direction of the X-axis but the material is shifted in the direction of the Z-axis. When a machining is simulated based on a machining program of a numerical control apparatus for controlling such machine tools, as shown in FIGS. 4 and 5, the tool is used to move in the direction of the Z-axis, instead of moving the material in direction of Z-axis, and therefore, a machining movement different from an actual machining movement is simulated by such conventional numerical control apparatuses.